TO PREPARE SALAD:,Preheat oven to 350°F,Place pita halves rough-side up on a large baking sheet. Brush with 1 tablespoon oil and sprinkle with 1 teaspoon sumac.,Bake until golden and crisp, about 15 minutes. When cool, break into bite-size pieces.,Whisk lemon juice, salt, pepper and the remaining 2 tablespoons oil and 1/4 teaspoon sumac in a large bowl.,Add lettuce, tomatoes, cucumber, onion, mint and the pita pieces; toss to coat. Let stand for 15 minutes.,______,Meanwhile, preheat grill to medium-high. Rub the chicken with oil and season with salt and pepper.,Grill until no longer pink inside, 3 to 4 minutes per side. (Alternatively, broil chicken 4 to 6 inches from the heat source for about 6 minutes per side.),Slice the chicken thinly and serve on top of the salad.,NOTE:.,The tart berries of the sumac bush add another element to many Middle Eastern dishes. Find them whole or ground in Middle Eastern markets or online at kalustyans.com or lebaneseproducts.com.,DIETARY EXCHANGES: 1 starch, 1 vegetable, 1 fat, 3 lean meat (1 Carbohydrate Serving).